1. Technical Field
The present invention relates to projection apparatuses and three-dimensional-shape detection apparatuses which can project a high-quality image onto a projection plane, suppressing variations in illumination of light applied from a semiconductor light-emitting element to a spatial modulation element.
2. Related Art
A previously known projection apparatus is configured to project a desired image onto a projection plane by performing spatial modulation of light coming from a Light source by means of a spatial modulation element. To be more detailed, this type of projection apparatus collects light coming from the light source by a light-collecting optical system, performs spatial modulation of collected light by means of the spatial modulation element in accordance with an image signal, and projects spatial-modulated light as image signal light onto the projection plane through a projection means.
The light source of the projection apparatus is used to be a xenon lamp, a halogen lamp, a metal halide lamp, or the like. Although this type of light source lasts short, it must be kept continuously on in the projection apparatus because on-off modulation cannot be performed. Accordingly, the conventional projection apparatus consumes much power.
Technologies disclosed in Japanese Patent Provisional Publication No. 11-32278 (hereafter referred to as document 1) and Japanese Patent Provisional Publication No. 11-231316 (hereafter referred to as document 2) solve the problem by using a semiconductor light-emitting element, or more specifically, a light-emitting diode (LED) as a light source of the projection apparatus.
The LED light source of the projection apparatus lasts longer and consumes less power. The light output from the LED has a strong directivity. Because the light-emitting area is small, the light collection efficiency is improved, consequently improving the light use efficiency.